I made a thread similar to this last week ( this one is actually better because it uses more accurate scans)
I can see three different routs kishi can take Naruto's powers
1) this route involves expanding on his rasengan, bijudama powers
We saw a lava rasenshuriken
Then we saw a bijudama rasenshuriken
Next is a bijudama lava rasenshuriken....
Basically, instead of using a single
Biju power at time, he will use multiple. Furthermore, we may see a planetary: bijudama rasengan.
The end result of taking naruto this way, would probably be omnyouton control
2) emphasis on yang
Naruto's ability to breath life may be expanded upon.
I think naruto is going to be able to breath life into his shadow clones. Making them act like real living individuals.
Naruto would also gain very good regeneration abilities if kishi takes him down this road
3) he gets the 6 paths powers
This theory is personally my favorite, basically it states that narutoay get the power of the six paths that are normally known to be given by the rinnegan.
This theory stems from the fact that naruto can fly, and that he is the successor of hogoromo. What is naruto is
Able to fly because of gravity control ? What if he developed the other paths powes. We already have seen gravity control ( flight ) and life
Giving ( regenerating Kakashi's eye)
Basically, naruto may learn chibaku tensei, energy absorption, soul absorption etc....